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Gas entrainment rate and flow pattern of vertical plunging liquid jets

Authors

  • Daisuke Kusabiraki,

    1. Department of Chemical Engineering, University of Niigata, 8050, Ikarashi Ni-no-cho, Niigata City 950–21, Japan
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  • Hidefumi Niki,

    1. Department of Chemical Engineering, University of Niigata, 8050, Ikarashi Ni-no-cho, Niigata City 950–21, Japan
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  • Kazuaki Yamagiwa,

    1. Department of Chemical Engineering, University of Niigata, 8050, Ikarashi Ni-no-cho, Niigata City 950–21, Japan
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  • Akira Ohkawa

    Corresponding author
    1. Department of Chemical Engineering, University of Niigata, 8050, Ikarashi Ni-no-cho, Niigata City 950–21, Japan
    • Department of Chemical Engineering, University of Niigata, 8050, Ikarashi Ni-no-cho, Niigata City 950–21, Japan
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Abstract

For a vertical plunging liquid jet system using various liquids, the effects of the operating conditions including the nozzle length-to-diameter ratio on the gas entrainment rate Qg were evaluated experimentally. The differences in Qg were related to the changes in the jet shape before plunging and the velocity of the plunging liquid jet at the point where the gas sheath breaks up. Empirical relationships were also presented to predict the maximum depth Z of bubbles entrained by the diffusing jet. The changes of Z were further discussed in terms of the downward liquid velocity distribution in the submerged two-phase region, which depends mainly on the size of entrained bubbles.

Abstract

On a évalué de faqon expérimentale pour un système à jet liquide plongeant utilisant des liquides variés, les effets des conditions d'opération, notamment le rapport entre la longueur et le diamètre de l'orifice sur la vitesse d'entraînement du gaz Qg. Les différences dans Qg ont été reliékes aux changements dans la forme du jet avant l'immersion et à la vitesse du jet liquide plongeant au point ou I'enveloppe du gaz se brise. On a également présenté des relations empiriques pour prédire la profondeur maximum Z des bulles entraînées par le jet diffusant. Les changements dans Z ont ensuite été examines par rapport à la distribution de la vitesse liquide descendante dans la region biphasique immergée, qui depend principalement de la taille des bulles entraînées.

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